Organic cyanine base



Patented Mar. 28, 194.4

ORGANIC CYANINE BASE Leslie G. S. Brooker and Robert H. Sprague, Rochester, N. Y., assignors to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey No Drawing. Original application April 18, 1941,

Serial No. 389,224. Divided and this application January 26, 1942, Serial No. 428,212

12 Claims.

This invention relates to organic bases and more particularly to what can be called cyanine bases, dialkylaminostyryl bases and dialkylaminophenylbutadienyl bases.

Cyanine bases, dialkylaminostyryl bases and 'dialkylaminophenylbutadienyl bases have been monium quaternary salts containing, in a reactive position, a thioether or a ,B-acylarylaminovinyl group. This method is of no utility for the preparation of diand tricarbocyanine bases, and in any event, is useful only for 'producing bases containing quinoline nuclei.

We have now found that a new kind of cyanine bases, dialkylaminostyryl bases and dialkylaminophenylbutadienyl bases can be prepared by condensing heterocyclic nitrogen bases containing in the alpha or gamma position, i. e. in one of the so-called reactive positions, a cyanomethyl group, with cyclammonium quaternary salts containing in a reactive position a group, such as halogen, thioether, ,S-arylaminovinyl, 'w-arylaminc-1,3-butadienyl or 3 arylamino-1,3,5 hexatrienyl. By our new method we can obtain readily cyanine bases containing long polymethine chains. Our new bases always contain a cyano group attached to one of the methine groups connecting the two cyclic nuclei, and are frequently much stronger sensitizers of photographic emulsions than the corresponding bases which are devoid of cyano groups. found thatbases devoid of cyano groups can be prepared from our new bases which contain a cyano group. Thus, we have provided many bases which were heretofore unavailable.

It is accordingly an object of our invention to provide new organic bases. A,further object is to provide a. process for preparing organic bases.

} Other objects will become apparent hereinafter.

In accordance with our invention, we prepare cyano cyanine bases by condensing a heterocyclic nitrogen base containing in a reactive position a cyanomethyl group, with a eyclammonium quaternary salt containing in a reactive position a member selected from the group consisting of We have also halogen atoms, thioether groups. fi-arylaminm,

vinyl (including acylated ,e-arylaminovinyl) groups, o-arylamino-L3-butadienyl (including acylated w-arylamino-Lii-butadienyl) groups. warylamino-1,3,5-hexatrienyl (including acylated o-arylamino-l,3,5-hexatri enyl) groups. Advantageously the condensations are effected in the presence of a'basic condensing agent. Tertiary organic basic condensing agents are advantageously employed especially with cyclammonium quarternary salts containing a halogen atom or a thioether group. Strong organic bases, 1. e. those having a dissociation constant substantially greater than that of pyridine, are advantageously employed. When employing strong organic bases, it isadvantageous to effect the condensations in a solvent, such as an alcohol oi the formula CnHim-HOH wherein n represents a positive integer of from one to three, for example. Heat accelerates the condensation.

The following examples will serve to illustrate our new cyanine bases and the manner of obtaining the same.

Exam ne 1.2-[cyano (.1-ethyl-4(1)-quinolylidene) methyl] quinoline and its hydrochloride 7.86 g. (1 mol.) of 4-phenylmercapt'oquinoline ethiodide, 3.36 g. (1 mol.) of 2-quinolvlacetonitrile and 2.0 g. (1 mol.) of triethylamine were placed in 25 cc. of absolute ethyl alcohol. The mixture was boiled, under reflux, for 10 minutes. The orange reaction mixture was cooled and. stirred with cc. of a 4% aqueous solution of sodium hydroxide. The aqueous liquors were decanted from the sticky brown precipitate. The precipitate was dissolved in 100 cc. of hot ethyl alcohol. Th solution was filtered while hot, and the cyanine ase precipitated as its hydrochloride by adding to/the filtered solution, 10 cc. of an alcoholic solution of hydrogen chloride (.-15 gram of hydrogen chloride per cc.). of the base separated at once. The mixture was then diluted to 200 cc. with acetone. The acetone mixture was chilled and filtered. In this manner a 72% yield of the hydrochloride was obtained. It was recrystallized from absolute ethyl alcohol (20 cc. per gram of hydrochloride) and obtained, in 62% yield, as brilliant coppery-red crystals melting with decomposition at 158 to 160 C.

1.0 g. (1 mol.) oi. the coppery-red crystals and Coppery crystals 0.6 g. (1 mol.+100% excess) of triethylamine were stirred together in 10 cc. of absolute ethyl -alcohol until solution was complete. -Th mixture was then poured into 300 cc. of water, whereupon the cyanine base precipitated. The base was filtered oil by suction. Yield 0.8 3., 89%.

The base was recrystallized from absolute ethyl orange solution in methyl alcohol, while the hydrochloride gave a bluish red solution.

4-quinolylacetonitrile can be prepared according to the method of Borsche and Biitschli, de-

scribed in Ann. 529, 271 (1937).

Exmrm '2.--2-[cyano-(3-ethyl 2(3) -benzothiazolylidene) methyl] benzothiazole Wail/W 5 6.4 g. (1 mol.) of 2-ethylmercaptobenzothiazole ethiodide, 3.5 g. (1 mol.) of 2-benzothiazolylacetonitrile and 2.0 g. (1 mol.) of triethylamine were placed in 100 cc. of absolute ethyl alcohol. The mixture was boiled, under reflux, for 15 minutes. Nearly colorless crystals of the base separated at once from the boiling mixture. The mixture was chilled, the base filtered ofl, washed with methyl alcohol and dried in the air. Yield of pale yellow crystals was 5.7 g., 85%. The base was recrystallized from acetone (75 cc. per gram of base) and obtained as glistening pale yellow needles, melting with decomposition at 219 to 221 C. Yield 4.7 g., 70%. The base gave a pale yellow solution in methyl alcohol. a. gelatino-silver-chloride emulsion slightly to 415 mu.

2-benzothiazolylacetonitriie can be prepared according to the method described by Borsche and Doeller, Ann. 537 54 (1938).

EXAMPLE 3.-2--[1 -cya1w-3- (1 -ethyl-4 (1 quinclylidene) propenz/Z] benzothiazole the air. Yield of green crystals was 1.8 g., 89%.-

After recrystallization from acetone (125 cc. per gram of base), the base was obtained as minute green crystals, melting with decomposition at 222 to 223 C. Yield 1.5 g., 74%. The base sensitized a photographic gelatino-silver-bromiodide emulsion fairly strongly between about 520 and about 680 mu, with a maximum at about 635 mu. The base gave a blue solution in methyl alcohol.

The base sensitized Exams: 4.2-[1-cyano-3- (3-ethyl-2(3) -benzo:c-

azolylidene) propenull-qulnoline 1 1 I ON 34 A} o \2CC3H 0211 i 2 5- 8 1.7 g. (1 mol.) of 2-quinolylacetonitrile, 4.34 g. (1 mol.) of 2-(p-acetanilidovinyl)-benzoxazole ethiodide and 1.0 g. (1 mol.) of triethylamine were placed in cc. of absolute ethyl alcohol. The mixture was. boiled, under reflux, for 10 minutes. The orange mixture was chilled, the base filtered off, the base washed with a small amount or absolute ethyl alcohol and dried in the air. The yield of orange crystals was 2.8 g., 82%. After recrystallization from acetone cc. per gram of base), the base was obtained as minute orange crystals, melting at 231 to 232 C. Yield 2.7 8., 79%. The base sensitized a photographic gelatino-silver-bromiodide emulsion very weakly out to about 560 mu, with some desensitization in the blue region. The base gave a yellow solution in methyl alcohol.

ExAMPLs 5.2-[1-c1 ano-3-(3 methyl-2 (3) thiazoZinz lidene) propem/ll quinoline s CYN nice a 2 1| 1.7 g. (1 mol.) of 2-quinolylacetonitrile, 3.9 g. (1 mol.) of 2-(s-acetanilidovinyl)-thiazoline methgodide and 1.0 g. (1 mol.) of triethylamine were placed in 15 -cc. of absolute ethyl alcohol. The mixture was boiled, .under reflux, for 10 minutes. The orange reaction' mixture was chilled, the cyanine base was filtered oil, the cyanine base washed with absolute ethyl alcohol and dried in the air. Yield of orange crystals was 2.9 g., 99%. After recrystallization from absolute ethyl alcohol (79 cc. per gram of base), the base was obtained, in 65% yield, as brown needles having a metallic reflex and melting with decomposition at 174 to 175 C. The base sensitized a photographic gelatino-silver-bromiodide emulsion ve y weakly out to about 560 mu, with considerable desensitization in the blue region. The base gave a yellow solution in methyl alcohol.

ExmLn 6.--2- [1 -cyano-3- (3-ethz/l-2 (3) -benzothiazolylidene) propenyl] quinoline 4.5 g. (1 mol.) of Z-(p-acetanilidovinyl) -benz0- thiazole ethiodide and 1.7 g. (1 mol.) of 2- quinolylacetonitrile were placed in 15 cc. of pyridine. The mixture was boiled, under reflux, for 3 minutes. The orange reaction mixture was cooled, diluted to 100 C. with water and chilled to 0 C. The aqueous liquors were decanted and the tarry residue was stirred with methyl alcohol until crystalline. The crystalline cyanine base was filtered on, washed'with water, then 3.0 g., 85% yield, oi a. reddish brown powder were thus obtained. Alter recrystallization irom methyl alcohol (250 cc. per gram of base), the base was obtained as red needles, having a green reflex and melting with decomposition at 175 to 176' C. Yield 2.0 g., 56%. The base sensitized a photographic gelatino-silver-bromlodide emulsion weakly out to about 620 mu.

2-quinolylacetonitriie can be prepared according to the method of Borsche and Manteuflel, Ann. 526, 36 (1936).

In a similarmanner, 4-[bcyano-3-(3-ethyl- 2(3) benzothiazoiylidene) propenyll quinollne was obtained from 4-quinoiylacetonitrile, in 45% yield, as red crystals, melting with decomposition at 188 to 190 C. This base sensitized a photographic gelatino silver bromiodide emulsion strongl out to 660 mu with a maximum of 540 mu.

EXAKPL! 7.--2- [1-cyano-5- (1 -ethyl-4 (1) -quinolylidene) -1,3-pe1itadienyll -benzothiazole S 1 1 ON {Y snake...)

1.74 g. (1 mol.) of z-benzothiazolylacetonitrile,

4.7 g. (l moi.) of 4-(4-acetanilido-L3-butadienyl) quinoline ethiodide and 1.0 g. (1 moi.)

of triethylamine were placed in 50 cc. of absolute obtained by extracting the crude product with 800 cc. of acetone and concentrating the 800 cc. to 150 cc. and chilling to C. In this manner 1.2 g., 32% yield,'of green crystals were obtained. After recrystallization from acetone (125 cc. per gram of base), the base was obtained as green needles melting at 201 to 203 C. with decomposition. Yield 0.6 g., 16%. The base sensitized a photographic gelatino-sllver-bromiodide emulsion strongly from about 680 mu to about 780 mu with a maximum at 740 mu. The base gave a. blue solution in methyl alcohol.

Exmnr: 8.2- [1 -cyano-- (1 -ethyZ-2 (1 -quinolylidene) -1,3-pentadienyllbenzothiazole 1.74 g. (1 mol.) of z-benzothiazolylacetonitrile, 4.7 g. (1 mol.) of 2-(4-acetanilido-l,3-butadienyl) quinoline ethiodlde and 1.0 g. (1 mol?) of triethyiamine were placed in 50 cc. of absolute ethyl alcohol. The mixture was boiled, under reflux, for 5 minutes. The cyanine base separated at once from the boiling mixture. The mixture was chilled, the base filtered oil, the base washed with methyl alcohol and dried in the air. Yield of green crystals 3.8 g., 100%. After recrystallization from acetone (300 cc. per g. of base), the base was obtained, in 58% yield, as green crystals melting at 230 to 233' C. with decomposition.

The base sensitized a photographic gelatino-silver-bromiodide emulsion strongly from 580 to 740 mu with a maximum at 640 mu. The base gave 5 a blue solution in methyl alcohol.

Exmrn 9.4-[1-cyano-5-(3-ethul-2-(3) -benzothiazolylidene) -1,3-pentadienyll 'quinoline 4.8 g. (1 mol.) of 2 (4-acetanilido) -1,3-butadienyl-benzothiazole ethiodide, 1.7 g. (1 mol.) of 4-quinolylacetonitrile and 1.0 g. (1 mol.) of triethylamlne were placed in 25 cc. of absolute ethyl 2.) alcohol. The mixture was boiled, under reflux, for 5 minutes. The red mixture was then cooled and diluted with 75 cc. 01 water. The diluted mixture was chilled to 0 C. and the aqueous liqmm were decanted. The residual green tar was 25 stirred with 25 cc. of hot acetone until completely crystalline. The acetone mixture was chilled, the crystalline cyanine base filtered oil and washed with acetone. Yield 1.9 g., 50%. After recrystallization from acetone (100 cc. per gram or base), the cyanine base was obtained as steel blue needles, melting with decomposition at 185 to 187 C. The base sensitized a photographic gelatino-silver-bromiodide emulsion feebiv out to 670 mu.

EXAMPLE 10.2-f1-cyano-7 (3-ethyl-2(3) -benzothiazolz/lidene) 1,3,5-heptatrienyll benzothiazole 1.74 g. (1 mol.) of 2-benzothiazoly1acetonitrile, 5.0 g. (1 mol.) of 2-6 -acetani1ido (1,3,5-hexatrienyl) benzothiazole ethiodide and 1.0 g. (1 mol.) triethylamine were placed in cc. of absolute ethyl alcohol. The mixture was boiled, under reflux, for 5 minutes. The cyanine base separated at once from the boiling mixture. The

mixture was chilled, the base filtered ofi, washed with methyl alcohol and dried in the air. Yield of copper bronze crystals was 3.3 g. This crude product was very impure. The base was obtained by extracting the crude product with 900 cc. of acetone, concentrating the acetone extract to 25 cc. and chilling to 0 C. In this manner 1.0 g., 24% yield, of green crystals was obtained. After recrystallization from acetone (140 cc. per gram of base), the base was obtained as minute blue crystals melting with decomposition at 193 to 195 C. Yield 0.7 g., 17%. This base sensitized a photographic gelatino-siiver-bromlodide emulsion strongly from 600 to 820 mu with a maximum at 760 mu. The base gave a blue solution in methyl alcohol.

EXAMPLE 1l.-4-[1-cyano-3-(1-ethyl-4(1) -quinolylidene) propenyl] quinoline alia-NI 2 3 4,5 g. (1 mol.) of 4-(p-acetanilidovinyl-quincline-ethiodide, 1.7 g. (1 mol.) of 4-quinolylacetonitrile and 1.0 g. (1 mol.) of triethylamine were placed in 15 cc. of absolute ethyl alcohol. The mixture was boiled, under reflux, for 5 minutes. The red mixture was cooled, diluted with 75 cc. of water, and the diluted mixture chilled to 0 C. The tar remaining after decanting the aqueous liquors, was stirred with 25 cc. of hot acetone until crystalline. The acetone mixture was chilled, the crystalline base flltered of! and washed with acetone. Yield 3 g., 86%. After recrystallization from methyl alcohol (115 cc. per gram of base), the base was obtained, in. 67% yield, as green crystals having a green reflex and melting at 178 to 180 C. with decomposition. The base gave a bluish red methyl alcoholic solution and sensitized a gelatino-silver-bromiodide emulsion slightly.

Exauru: 12'.2-[1-cyano-3-(3-ethyl 2(3) benzothiazolylidene) propenyll-beneothiazole 9.0 g. (1 mol.)-of Z-(p-aoetanilidovinyl) -benzothiazole ethiodide,'3.5 g. (1 mol.) of 2-benzothiazolylacetonitrile and 2.0 g. (1 mol.) of triethylamine were placed in 100 cc. of absolute ethyl alcohol. The mixture was boiled, under reflux, for 15 minutes. Blue crystals of base separated at once from the boiling mixture. The mixture was chilled, the base filtered off washed with methyl alcohol and dried in the air. Yield 6.4 g., 89%. After crystallization from acetone (100 cc. per gram of base), the base was obtained as red needles, having a silver reflex, and melting at 210 to 212 C. with decomposition. Yield 4.8 g., 67%. The base gave a pink solution in methyl alcohol. The base sensitized a gelatino-silverbromiodide emulsion out to 600 mu with a maximum at 550 mu.

EXAMPLE 13.--2- [1 -cz!an0-5- (B-ethyZ-Z (3) -benaothiazolylidene) -1,3-pentadienyl] -benzothiazole 10.4 g. (1 mol.) of 2-(4-acetanilido-1,3-butadienyD-benzothiazole etho-p-toluene-sulfonate, 3.5 g. (1 mol.) of Z-benzothiazolylacetonitrile and 2.0 g. (1 mol.) of triethylamine were placed in 100 cc. of absolute ethyl alcohol. The mixture was boiled, under reflux, for 15 minutes. Blue crystals of the base separated at once from the boiling solution. The mixture was chilled, the base filtered off, washed with methyl alcohol and dried in the air. The crude product was boiled with 200 cc. of methyl alcohol, filtered from the hot methyl alcohol and dried in the air. Yield of blue crystals was 5.5 g., 72%. After crystallization from acetone (150 cc. per gram of base), the base was obtained as blue needles, melting with decomposition at 205 to 206 C. Yield 5.2 g., 69%. The base gave a purple solution in methyl alcohol and sensitized a gelatinosilver-bromiodide emulsion fairly strongly to 700 mu with a maximum at 650 mu.

Exam 14.-2-[1 cyano-541 ethlll 2(1)-pnaphthothiazolylidene) 1,3-pentadienyll-bem zothiazole 5.3 g. (1 mol.) of 2-(4-acetanilido-1,3-butadienyD-p-naphthothiazole ethiodlde, 1.74 g. (1 mol.) of 2-benzothiazolylacetonitrlle and 1.0 g. (1 mol.) of triethylamine were placed in 100 cc. of absolute ethyl alcohol. The mixture was boiled, under reflux, for 15 minutes. The base separated at once from the boiling mixture. The mixture was chilled, the base filtered oil, washed with methyl alcohol and dried in the air. Yield of dark crystals 3.5 g., 80%. After crystallization from pyridine (95 cc. per gram of base), the base was obtained as dull blue crystals melting with decomposition at 240 to 242 C. Yield 2.1 48%. alcohol and sensitized a gelatino-silver-bromiodide emulsion fairly strongly between about 560 mu and 710 mu with a maximum at 670 mu.

In a similar manner 2-(B-acetanilidovinyD-3- phenylbenzothiazolium iodide can be condensed with 2-benzothiazolylacetonitrile to give 2-[1- cyano 3-(3-phenyl 2(3)-benzothiazolylidene) propenyll -benzothiazole. 2- (p-acetanilidovinyl) 3-phenylbenzothiazolium iodide is described in the co-pending application of Leslie G. S. Brooker and William W. Williams, Serial No. 353,500, filed August 21, 1940 (now U. S. Patent 2,330,203, dated September 28, 1943).

In accordance with our invention dialkylaminostyryl and dialkylaminocinnamyl bases can be prepared by condensing dialkylaminobenzalde-' hydes or dialkylaminocinnamic aldehydes with heterocyclic nitrogen bases containing, in a reactive position, a cyanomethyl group. These condensations are advantageously effected in the presence of a water-binding agent, e. g. a waterbinding agent comprising an anhydride of a monocarboxylic organic fatty acid. Alternatively these condensations are advantageously effected in the presence of a catalyst comprising essentially a strong secondary organic base, such as plperidine. When employing such a catalyst, the condensations are advantageously effected in a solvent, such as an alcohol of the formula CnHiln+1OH wherein n represents a positive integer of from one to three. Heat accelerates the condensations.

The following examples will serve to illustrate our new cyano dialkylaminostyryl and cyano dialkylaminocinnarnyl bases and the manner of obtaining the same.

Exaurns 15.4-[1 cyano-(p dimethylamino) styryllquinoline s 5 ON 1.7 g. (1 mol.) of 4-quinolylacetonitrile and 3 g. (1 mol.+% excess) of p-dimethylaminobenzaldehyde were placed in 15 cc. of acetic anhydride. The mixture was boiled, under reflux, for one hour. The brownish mixture was chilled to 0 C. when greenish yellow crystals of styryl base separated. These were filtered off and re- The base gave a blue solution in methyl crystallized from methyl alcohol (43 cc. per gram of base). The base was thus obtained, in 47% yield, as yellow flakes meltins'at 153 to 154 C. The base sensitized a gelatino silver-bromiodide emulsion weakly out to 540 mu.

Exams: 16.2-[1-cyano-4(p dimethylaminm- LB-utadtenyllbenzothiazolra 1.5 g. (1 mol.) of fi-benzothiazolylacetonitrile, 1.5 g. (1 mol.) of p-dim'ethylaminocinnamaldehyde and 10 drops of piperidine were placed in 25 cc. of absolute ethyl alcohol. The mixture was boiled, under reflux, for 10 minutes. The cinnamyl base separated at once from the boiling mixture. The orange mixture was chilled, the base filtered off, washed with methyl alcohol and dried in the air. Yield of minute dark crystals 2.3 g., 81%. After recrystallization from acetone (225 cc. per gram of base), the base was obtained, in 53% yield, as minute purple crystals, melting with decomposition at 226 to 228 C. The base sensitized a photographic gelatino-silver-bromiodide emulsion very weakly out to 640 mu, with considerable desensitization in the blue region. The base gavean orange solution in methyl alcohol.

Any of the cyano cyanine bases, cyano styryl bases or cyano cinnamyl bases of our invention can be converted into the corresponding dyes by quaternarization with allwl salts. The following examples will serve to illustrate the manner of obtaining such dyes.

EXAMPLE l7.10-llan0-3-ethyl-1-methylthia-4'- carbocuanine bromide I benzothiazolylidene) propenyll quinoline and 0.4 8. (1 mol.+100%) of methyl-p-toluenesulfonate were heated together at 125 to 130 C. for about 2 hours. The green solid mass was cooled and stirred with diethyl ether. The solid residue was dissolved in 5 cc. of hot methyl alcohol. A hot aqueous solution of potassium bromide was added to the methyl alcoholic solution. The dye which precipitated was filtered oif, washed with water and acetone and then dried in the air. After recrystallization from methyl alcohol (20 cc. per gram of dye) the dye was obtained as purple crystals with a bronze reflex and melting with decomposition at 262' to 263' C. The dye gave a bluish red solution in methyl alcohol. Yield 0.25 g., 55%. The dye sensitized a gelatino-silverbromiodide emulsion weakly out to 650 mu with a maximum at 620 mu.

Exams: 18.---cyano-3,3'-dethylthiacarbo- 1.2 8. (1 11101.) of 2-[1-cyano-3-(3-ethyl-2t3)- benzothiazolylidene) propenyll -benzothiazo1e and 1.5 g. (1 mol.+200% excess) of diethyl sulfate were heated together for 9 hours on a steam bath.

After cooling, the mixture was washed by de- 5 cantation with several 50 cc. portions of absolute diethyl ether. The washed mixture was then dissolved in 80 cc. of hot methyl alcohol. To the hot methyl alcoholic solution was added an excess of sodium iodide in methyl alcoholic solution. The dyeiodide precipitated. The dye was filtered oil, washed with water, then with acetone and dried in the air. Yield of red crystals 1.1 g., 65%. After recrystallization from methyl alcohol (330 cc. per gram of dye), the dye was ob tained as steel blue crystals melting with decomposition at 219 to 222 C. Yield0.9 g., 53%. The dye gave a red solution in methyl alcohol. The dye sensitized a gelatino-silver-bromiodide emulsion out of 600 mu with a maximum at 550 mu.

Our new cyano bases can be represented by the following general formulas:

Q. ON Z wherein d and e each represent a positive integer of from 1 to 2, n represents a positive integer of from 1 to 4, 121. represents a positive odd integer of from 1 to '3, D represents an arylene group, L represents a methine group, R represents an organic radical selected from the group consisting of alkyl and aryl groups, R and R." each represent an alkyl group and Q and Z each represent the non-metallic atoms necessary to complete a heterocyclic nucleus.

o In accordance with our invention, the cyano cyanine bases, cyano styryl bases or cyano cinnamyl bases are hydrolyzed to the corresponding unsubstitute bases. During the hydrolysis. the cyano group is converted to a carboxyl group which loses carbon dioxide. The hydrolysis is advantageously efiected with an acid hydrolysis catalyst. Mineral acids are advantageously employed as acid hydrolysis catalysts. Heat accelerates the hydrolysis.

The following examples will serve to illustrate the manner of obtaining unsubstituted bases from the cyano bases.

ExAurLr: 19.2-[3-(3-ethul-2(3) -benzothiazolulidene) propenvl] quinoline 1.0 g. of 2-[1-cyano-3-(3-ethyl-2(3) -benzothiazolylidene) propenyll quinoline was placed in 50 cc. of 60% sulfuric acid. The mixture was heated to boiling, under reflux. A vigorous evolution of carbon dioxide occurred at the boiling point. The mixture was boiled until the evolution of carbon dioxide ceased (about 5 minutes). The mixture was then poured onto ice and made alkaline with ammonium hydroxide. The orange precipitate was filtered off, washed with water and dried. In this manner 0.9 g., 97% yield, of greenish solid was obtained. After recrystallization from absolute ethyl alcohol (17 cc. per gram of base), the

EXAMPLE 20.4-[5-(3-ethyl-2i3)-benz0thiazolylidene) -1,3-pentadienyll quinoline 0.6 g. of 4-[1-cyano-5-(3-ethyl-2G) -benzothiazolylidene) =1,3-pentadienyll quinoline were placed in 30 cc. of 60% sulfuric acid. The mixture was boiled, under reflux, for one minute. The solution was then cooled, poured onto ice, and made alkaline with ammonium hydroxide. The cyanine base was filtered off. Yield of greenish solid was 0.5 g., 89%. The base was recrystallized from methyl alcohol (100 cc. per gram of base), and obtained, in 36% yield, as a dull red powder, melting with decomposition at 187 to 189 C. The base had no sensitizing action on photographic silver halide emulsions.

EXAMPLE 2 1.2- (1 -ethyli (1) -quinolylidene) methyl] -quino1ine 2 g. of 2-[cyano-(1-ethyl-4G)-quinolylidene) methyl] quinoline hydrochloride were placed in 75 cc. of 60% sulfuric acid. The mixture was boiled, under reflux, for minutes. The mixture was then cooled, poured onto ice and made alkaline with ammonium hydroxide. The cyanine base was filtered off. Yield 1.6 g., 97%. After recrystallization from absolute ethyl alcohol (17 cc. per gram of base), the base was obtained as red crystals having a greenish reflex and melting at 110 to 111 C. with decomposition. Yield 1.2 g., 73%. The base had a very slight sensitizing action on photographic silver halide emulsions.

EXAMPLE 22.2-[5-(3-eth11Z-2(3) -benzothiazolylidene) -1,3-pentadienyl] -quirwlz'ne 4.2 g. of 2-[1-cyano-5-(3-ethyl-2(3)-benzothiazolylidene) -l,3-pentadienyll -quinoline were placed in 150 cc. of 60% sulfuric acid. The mixture was boiled, under reflux, for 5 minutes. The mixture was cooled, poured onto ice, and made alkaline with ammonium hydroxide. The

aesaooa crude cyanine base was filtered on. It was contaminated with considerable insoluble colorless material. The crude product was extracted with 100 cc. of absolute ethyl alcohol. Upon chilling 5 the alcoholic extract red crystals oi cyanine base separated. These were filtered of! and recrystallized from absolute ethyl alcohol (65 cc. per gram of base) and obtained as minute red crystals melting at 142 to 144 C. with decomposition. Yield 1.2 g., 31%. The base sensitized a photographic gelatino-silver-bromiodide emulsion fairly strongly between about 560 mu and 760 mu with a maximum at about 710 mu.

In a similar manner, 2-[5-(1-ethyl-2(1)-quinolylidene)-l,3-pentadieny1l benzothiazole was obtained as a dull black powder melting with decomposition at 153 to 155 0., from 2-[l-cyanobenzothiazole.

EXAMPLE 23.-2 [a (p-dimemyzemmophenul) 1.3-butaaie1wll beneothiazole) 2.0 g. of 2-il-cyano-d-(p-dimethylaminophenyl)-1,3-butadienyll benzothiazole and 150 cc. of 60% sulfuric acid were mixed together. The mixture was boiled, under reflux, until evolution of carbon dioxide ceased (about 5 minutes). The mixture was then cooled rapidly and poured onto a mixture of crushed ice and water containing ammonium hydroxide in excess of that required to neutralize the sulfuric acid. The base precipitated. it was filtered off, washed with water and dried in the air. Yield of green crystals was 0.7 g., 38%. The base was recrystallized from methyl alcohol (500 cc. per gram of base) and obtained, in 27% yield, as greenish crystals melting with decomposition at 173 to 175 C. Its methyl alcoholic solution was yellow. It sensitized a photographic silver halide emulsion very slightly.

EXAMPLE 2'4.2 [7 (3-ethyl-2(3) -benzothiazolylidene) -1,3,5-heptatrienyll benzothiazole 6 i wr..eaasaaiaas/ 54 \g/ 1.0 g. of 2-[1-cyano-7-(3-ethyl-2(3) -benzothiazolylidene) -1,3,5-heptatrienyl] benzothiazole and 100 cc. of 60% sulfuric acid were mixed together. The mixture was boiled, under reflux, until evolution of carbon dioxide ceased (about 3 minutes). The mixture was cooled rapidly and poured onto a mixture of crushed ice and water containing ammonium hydroxide in excess of that required to neutralize the sulfuric acid. The base precipitated. It was filtered oil, washed with water and dried in the air. Yield .4 g., 43%. After recrystallization from acetone (800 cc. per gram of base), the base was obtained as dull black crystals, melting with decomposition at 141 to 142 0. Yield 0.3 g., 32%. Solution in methyl alcohol was red. Gave no sensitizing action on a photographic silver halide emulsion.

In the preparation of photographic emulsions sensitized with the herein described bases, it is only necessary to disperse the bases in the emul- 75 sions. It is convenient to add the bases to the emulsions from solutions in appropriate solvents. of from 1 to 2, n represents a positive integer of Acetone and methyl alcohol have proven satisfrom 1 to 4, Lrepresents a methine group, Rrepfactory as solvents for this purpose. Sensitization resents an organic radical selected from the group by means of these bases is, of course, primarily consisting of alkyl and aryl groups, and Q and Z directed to the ordinarily employed gelatino-sil- 5 each represents the non-metallic atoms necessary ver-halide developing-out emulsions. The bases to complete a heterocyclic organic nucleus.

, are ordinarily incorporated in the washed, fin- 2. A process for preparing a cyanine base comished emulsions and should, of course, be uniprising hydrolyzing, in the presence of 'a mineral formly distributed throughout the emulsion. The acid hydrolysis catalyst, a cyano base of the folconcentration of the bases in the emulsions can lowing general formula: vary widely, i. e. from about 5 to about 100 mg.

per liter of flowable emulsions. The concentra- ON J/z\\ tion of the basev will vary according to the type of n-N1. L-' -L c r, hght'sensmve material in the emulsm-n and ac wherein d and e each represents a positive integer cording to the efiect desired. The suitable and 1 most economical concentration for any given of from to 2, n represents a positive integer of emulsion will be apparent to those skilled in the from 1 to 4, L represents a methine group, R repart upon making the ordinary tests and observa 23: 5: 3: gi g g ggifggf gggg fi customarily employed in art of g each represents the non-metallic atoms necessary mafikliiig- 5308152 5 2 t1? ogg gg f g s g 'i to complete a heterocyclic organic nucleus.

em on n 3. IA process for preparing a cyanine base comfollowing procedure is satisfactory. A q y 0f prising hydrolyzing, in the presence of a sulfuric the base is dissolved in acetone or other suitable acid hydrolysis catalyst, a cyano base of the folsolvent, and a volume of this solution (it may be lowing general formula:

diluted with water) containing from 5 to 100 mg. 25

of base is slowly added to about 1000 cc. of gelat- Z c lno-silver-halide emulsion, with stirring. Stirrin'g )i-|-G=(L-L)..-.= c= L-L).-1=N

is continued until the base is uniformly distributed wherein at and e each re resents a sitive inte er throughout the u 1th most these of from 1 to 2, n repres ents a positive integer of sensitlzmg bases 10 20 of per mar from 1 to 4, L represents a methine group, R repemulsion sufi'lces to Produc? the mamm um 1 resents an organic radical selected from the group tizing effect with the Ordinary f f consisting of alkyl and aryl groups, and Q and Z bromide (in bIOmiOdid?) 6111111510115 Wlth each represents the non-metallic atoms necessary gelatino-silver-chloride emulsions somewhat largto complete a heterocyclic organic nucleus.

or concentrations are required to produce the op- 4 A process for preparing tflcarbocyanlne timum sensitizing effect. The above statements base comprising hydrolyzing, in the presence of are only illustrative and are not to be understood an acid hydrolysis catalyst, at tricarbocyanine as limiting our invention, as it will be apparent base having the following formula:

that these bases can be incorporated by other methods in the photographic silver halide emulof, from 1 to 2, R represents an alkyl group and Q sions customarily employed in the art. For inand Z each represents the non-metallic atoms stance, the bases may be incorporated by bathing necessary to complete a heterocyclic nucleus.

3, plate or film upon which an emulsion has been 5. A process for preparing a tricarbocyanine coated in a solution of the base in an appropriate base comprising hydrolyzing, in the presence of solvent. Bathing methods, however, are not to be a mineral acid hydrolysis catalyst, a tricarbocypreferred ordinarily. anine base having the following formula:

wherein d and e each represents a positive integer herein at and e each represents a positive integer This application is a division of our copending w application Serial No. 389,224, filed April 18, 1941. mm 1 R represents an i and Q What we claim as our invention and desire to and 2 each represents the non'metamc atoms be secured by Letters Patent of the United States necessary hetemycnc 6. A process for preparing a tricarbocyanine base comprising hydrolyzing in the presence of a 1. A recess for re ar a c anine b e comprising phydmlyzing g g i acid sulfuric acid hydrolysis catalyst, a, tricarbocyanine base having the following formula:

hy r ly y t. a cyano base of the following wherein d and e each represents a positive integer general formula: of from 1 to 2, R represents an alkyl group and Q Q 0N z and Z each represents the non-metallic atoms .2: necessary to complete a heterocyclic nucleus. C (L L)"N 7. A process for preparing a dicarbocyanine wherein d and 2 each represents a positive integer base comprising hydrolyzing, in the presence of an acid hydrolysis catalyst, a dicarbocyanine hose having the following formula:

wherein d and e each represents a positive integer of from 1 to 2. It represents an alkyl group and Q wherein d and e each represents a positive integer 01' from 1 to 2, R represents an alkyl group and Q and Z each represents the non-metallic atoms necessary to complete a heterocyclic nucleus.

9. A process for preparing a dicarbocyanine base comprising hydrolyzing, in the presence of a sulfuric acid hydrolysis catalyst, a dicarbocyanine base having the following formula:

Q CN

and Z each represents the non-metallic atoms necessary to complete a heterocyclic nucleus.

11. A process for preparing a carhocyanine base comprising hydrolyzing, in the presence or a min 10 eral acid hydrolysis catalyst, a carbocyanine base having the following formula:

wherein it and e each represents a positive integer 29 of from 1 to 2, R represents an alkyl group and Q and Z each represents the non-metallic atoms necessary to complete a heterocyclic nucleus.

12. A process for preparing a carbocyanine base comprising hydrolyzing, in the presence of a sulwherein d and e each represents a positive integer iuric acid hydrolysis catalyst, a carbocyanine or from 1 to 2, R represents an alkyl group and Q 30 base having the following formula:

and Z each represents the non-metallic atoms necessary to complete a heterocyclic nucleus.

10. A process for preparing a carbocyanine base comprising hydrolyzing, in the presence of an acid hydrolysis catalyst, a carloocyanine base having so or from 1 to 2, R represents an alkyl group and Q the following formula:

and Z each represents the non-metallic atoms necessary to complete a heterocyclic nucleus.

LESLIE G. S. BROOER. ROB%T H. SPRAGUE. 

